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yasir9909
Joined: 04 Jan 2010
Posts: 9
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| Operating PIC18F2550 at 8MHz with internal osc in CCS? |
 Posted: Sat Mar 22, 2014 3:56 am |
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Hi,
I am new to CCS Compiler, previously I used to use mikroC for PIC.
I want to operate my PIC18F2550 at 8MHz with internal oscillator.
what fuses and configuration bits I need to set for this purpose?
Currently, I have developed an application in CCS Compiler for PIC18F2550 but my PIC18F2550 is operating at 2MHz with internal oscillator. I need to operate PIC18F2550 at 8MHz with internal oscillator.
How can it be done?
regards
m.yasir |
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Mike Walne
Joined: 19 Feb 2004
Posts: 1785
Location: Boston Spa UK
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| Posted: Sat Mar 22, 2014 6:43 am |
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Which compiler are you using?
These two lines should do it:-
| Code: | #fuses INTRC
#use delay(clock=8000000) |
If not you may have to use
| Code: | | setup_oscillator(OSC_8MHZ); |
Mike |
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yasir9909
Joined: 04 Jan 2010
Posts: 9
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| Posted: Sat Mar 22, 2014 1:22 pm |
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I am using CCS C Compiler version 5.015
I have tried following configurations and fuses settings for oscillator:
#fuses NOWDT
#use delay(internal=8MHz)
but these settings didn't work
I have also tried the following settings:
#fuses INTRC,NOWDT,NOPROTECT,NOMCLR
#use delay(clock=8MHz)
these settings didn't work either
regards
m.yasir |
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Mike Walne
Joined: 19 Feb 2004
Posts: 1785
Location: Boston Spa UK
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| Posted: Sat Mar 22, 2014 5:32 pm |
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Setup_oscillator() allows you to change frequency on the fly.
If all else fails look at the appropriate registers and play with them.
Mike |
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temtronic
Joined: 01 Jul 2010
Posts: 9243
Location: Greensville,Ontario
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| Posted: Mon Mar 24, 2014 5:26 am |
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Please post a very small, compilable program(1HZ LED) that doesn't work for you that shows all the fuses.
It is possible that another 'fuse' is overriding your configuration.
hth
jay |
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yasir9909
Joined: 04 Jan 2010
Posts: 9
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| Posted: Wed Mar 26, 2014 4:17 am |
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Here is the simple code for character loop back in CCS for PIC Compiler Version 5.015:
| Code: |
// character loop back test
#if defined(__PCM__)
#include <18F2550.h>
#fuses NOWDT,INTXT
#use delay(internal=8000000)
#use rs232(baud=38400, xmit=PIN_C6, rcv=PIN_C7)
#include <C:\Program Files (x86)\PICC\Drivers\stdlib.h>
#include <C:\Program Files (x86)\PICC\Drivers\math.h>
#include <C:\Program Files (x86)\PICC\Drivers\stdio.h>
#define compiler __PCM__
#elif defined(__PCB__)
#include <18F2550.h>
#fuses NOWDT,INTXT
#use delay(internal=8000000)
#use rs232(baud=38400, xmit=PIN_C6, rcv=PIN_C7)
#include <C:\Program Files (x86)\PICC\Drivers\stdlib.h>
#include <C:\Program Files (x86)\PICC\Drivers\math.h>
#include <C:\Program Files (x86)\PICC\Drivers\stdio.h>
#define compiler __PCB__
#elif defined(__PCH__)
#include <18F2550.h>
#fuses NOWDT,INTXT
#use delay(internal=8000000)
#use rs232(baud=38400, xmit=PIN_C6, rcv=PIN_C7)
#include <C:\Program Files (x86)\PICC\Drivers\stdlib.h>
#include <C:\Program Files (x86)\PICC\Drivers\math.h>
#include <C:\Program Files (x86)\PICC\Drivers\stdio.h>
#define compiler __PCH__
#elif defined(__PCD__)
#include <18F2550.h>
#fuses NOWDT,INTXT
#use delay(internal=8000000)
#use rs232(baud=38400, xmit=PIN_C6, rcv=PIN_C7)
#include <C:\Program Files (x86)\PICC\Drivers\stdlib.h>
#include <C:\Program Files (x86)\PICC\Drivers\math.h>
#include <C:\Program Files (x86)\PICC\Drivers\stdio.h>
#define compiler __PCD__
#endif
void main()
{
char value;
setup_oscillator( OSC_8MHZ );
printf("\r\nStart typing:\r\n");
while(TRUE)
{
while(!kbhit());
value = getc();
putc(value);
}
}
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This piece of code simply loops back what you type on serial interface software like 'PLC Test' (or through your own program written in Labview for this purpose) when the microntroller hardware is connected with serial port of PC.
The issue that I am facing is that the baud rate being generated through above piece of code is 1/4th of what I intend to configure the micrcontroller for.
I have set the baud rate to 38400 but in actual I am getting 9600 ( = 38400/4) baud rate which is 1/4th of what I have configured my controller for through above piece of code. |
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Ttelmah
Joined: 11 Mar 2010
Posts: 19538
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| Posted: Wed Mar 26, 2014 5:12 am |
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Start by getting rid of all the if/else's.
They won't work, and are just confusing you. PCB, PCM, and PCD, all cannot compile code for the 18 family chips.
KISS.
Then since you don't have an external crystal, as you have already been told, use INTRC.
You do realise, that you cannot use USB on this chip without an external oscillator/crystal?. So pointless to enable the USB voltage regulator etc.. Just wastes power. If you have an external crystal, then why run the CPU off the internal (low accuracy) oscillator?. You also realise that the internal oscillator, is _only just_ accurate enough for RS232, if the unit is in a 'room temperature' environment?.
| Code: |
#include <18F2550.h>
#fuses NOWDT,INTRC,NOLVP,NOXINST,NOVREGEN,NOPDADEN
#use delay(internal=8000000)
#use rs232(baud=9600, UART1, ERRORS)
#include <C:\Program Files (x86)\PICC\Drivers\stdlib.h>
#include <C:\Program Files (x86)\PICC\Drivers\math.h>
#include <C:\Program Files (x86)\PICC\Drivers\stdio.h>
void main(void)
{
char value;
printf("\r\nStart typing:\r\n");
while(TRUE)
{
while(!kbhit());
value = getc();
putc(value);
}
}
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Merrily runs at 9600bps, on both 5.014, and 5.016 (the two nearest versions I have to your compiler)... |
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temtronic
Joined: 01 Jul 2010
Posts: 9243
Location: Greensville,Ontario
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| Posted: Wed Mar 26, 2014 5:25 am |
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At first I thought the fuse INTXT was in error, so I looked at the 4550, as it's the bigger brother of the 2550. It's a valid fuse but I do recall when using the 4550 there are a LOT of fuses! I don't know what INTXT really does.
edit: OK, Mr. T replied while I got my coffee refilled ! I read the fuses.txt file and it is 'silly' to have that configuration.Having a real crystal (and caps) on board is always better. The time 'saved' by using the internal osc is only a few ms..hardly worth the effort in my opinion,especially if you have PUT enabled!
When I finally got a valid, working set of fuses, I put them in a separate file (4550_program_name.fuz) and just #included it. It saves a lot of visual clutter in the program and I _know_ they work.
You should printout the listing or examine them in MPLAB to see what the REAL 'fuses' configuration is. I know the 4550 will run fine using the internal 8MHz oscillator, so I suspect a faulty 'configuration', either by not selecting them correctly of a compiler 'bug'.
Also , if you're only using one compiler, you should remove the long conditional IF-ELSE at the beginning.One wrong 'typo' can cause you problems!
hth
jay
Last edited by temtronic on Wed Mar 26, 2014 5:37 am; edited 1 time in total |
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Ttelmah
Joined: 11 Mar 2010
Posts: 19538
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| Posted: Wed Mar 26, 2014 5:31 am |
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INTXT is 99% the same as INTRC. However it sets both the oscillator I/O bits for oscillator use, rather than for I/O, enables the XT oscillator, and requires a crystal on the OSC pins. to run the USB. It is slightly pointless, since once you have such a crystal, you might as well run the CPU off it!.... 
It's designed for systems where you might want to get the fastest boot, for the CPU, by using the RC oscillator, but still want to use USB, or are going to disable the USB at times. Normally you'd switch oscillators as soon as the crystal is running and stable, if using this.
Best Wishes |
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yasir9909
Joined: 04 Jan 2010
Posts: 9
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| @ Ttelmah |
| Posted: Fri Mar 28, 2014 3:05 am |
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Ttelmah,the code that you have posted does not work either as it gives error for "NOPDADEN "
The actually working code that I have tried is given below
| Code: |
// character loop back test
#include <18F2550.h>
#fuses NOWDT,NOPROTECT,NOLVP
#use delay(internal=8000000)
#use rs232(baud=9600, xmit=PIN_C6, rcv=PIN_C7)
#include <C:\Program Files (x86)\PICC\Drivers\stdlib.h>
#include <C:\Program Files (x86)\PICC\Drivers\math.h>
#include <C:\Program Files (x86)\PICC\Drivers\stdio.h>
void main(void)
{
setup_oscillator( OSC_8MHZ|OSC_INTRC,OSC_STATE_STABLE );
char value;
printf("\r\nStart typing:\r\n");
while(TRUE)
{
while(!kbhit());
value = getc();
putc(value);
}
}
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This code is working fine at 8MHz on internal oscillator and serial port is operating at a baud rate of 9600. |
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rnielsen
Joined: 23 Sep 2003
Posts: 852
Location: Utah
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| Posted: Fri Mar 28, 2014 8:36 am |
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I believe Ttelmah did a 'fat finger'. It should be NOPBADEN. This sets portb as digital I/O instead of analog(PBADEN).
Ronald |
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